An inflatable vehicle occupant restraint, such as an air bag, is inflated when the vehicle experiences a collision. Inflation fluid is then directed to flow from a source of inflation fluid into the air bag. The inflation fluid increases the internal fluid pressure of the air bag and inflates the air bag to an inflated condition. When the air bag is in the inflated condition, it extends into the vehicle occupant compartment at a location adjacent to an occupant of the vehicle. The internal fluid pressure attained by the inflated air bag is controlled so that the inflated air bag can protect the occupant from a forceful impact with parts of the vehicle as result of the collision.
In certain applications, an air bag is inflated when the vehicle experiences a side impact collision, such as a collision in which an impact is directed against a door at the side of the vehicle. A side impact collision can cause the door to intrude toward the middle of the vehicle. The air bag is inflated into the vehicle occupant compartment at a location between the door and an occupant of a seat adjacent to the door. The air bag is thus inflated into the vehicle occupant compartment so as to protect the occupant from being forcefully struck by the intruding door.
When an air bag is inflated to protect a vehicle occupant in the foregoing manner, the air bag is subjected to the force of the intruding door moving against the air bag and the force of the air bag moving against the occupant. The forces applied to the air bag can cause the internal fluid pressure of the air bag to increase substantially. Therefore, it may be desirable to control the internal fluid pressure of the air bag by venting the inflation fluid outward from the air bag.